A three-phase coaxial superconducting power cable denotes a superconducting cable that has a structure in which three superconducting layers form a layer with respect to one axis, and includes an electricity insulating layer formed of an electricity insulating material between adjacent superconducting layers. The three-phase coaxial superconducting power cable reduces the number of wires by about half compared to other superconducting cables of the related art, and decreases the number of used insulating papers by about two-third of a three-phase batch type, thus reducing a diameter of a core to enable an economical and compact superconducting power cable to be realized.
Moreover, since a vector sum of a three-phase current is close to 0 and a current flowing in a shield layer is low, the three-phase coaxial superconducting power cable does not include a superconducting shield layer winding, and includes a shield layer formed of copper which surrounds all of three phases externally. Also, since a three-phase combination process is unnecessary, a manufacturing process is simplified, thus greatly reducing the manufacturing cost.
FIG. 1 illustrates a structure of a related art three-phase coaxial superconducting power cable. The related art three-phase coaxial superconducting power cable includes a superconducting layer 100, an electricity insulating layer 110, a copper shield layer 120, and a cryo-chamber 130.
The superconducting layer 100 is provided as three, and has a structure in which a layer is formed with respect to one axis. The superconducting layer 100 includes a superconducting wire, and a current flows through the superconducting wire. When an input current is lower than a critical current, the superconducting wire shows a superconducting characteristic in which a resistance is 0, but when the input current is higher than the critical current, the superconducting characteristic is broken. The electricity insulating layer 110 is disposed between adjacent superconducting layers 100, and filled with an insulating material for insulation.
In the related art three-phase coaxial superconducting power cable, when a high voltage flows in each of the superconducting layers 100, the electricity insulating layer 110 becomes thicker, and for this reason, a radius difference between the superconducting layers 100 enlarges. Also, since each of the superconducting layers 100 has a superconducting wire to be suitable for a circumference, the numbers of superconducting wires of respective phases differ. For this reason, the respective phases have different critical currents, and moreover a waste of superconducting wires occurs in an outer layer.